Telephone switching system.



H. P. CLAUSEN.

TELEPHONE SWITCHING SYSTEM. APPLICATION FILED JUNE 7,19l5.

1,21%,51 1. Patented Feb. 6, 191?.

W/Messea- //1ve/1/0/ Q-Q M E m y f? C/amsen. -W y W HENRY PETER CLAUSEN, OF IIIOUNT VE anon, nnwvenx, ASSIGNOR, BY MESNE ASSIGNMENTS, T WESTERN ELECTRIC COMPANY, IN CORPOBATED, A GORPORA- TION OF NEW YORK.

TELEPHONE SWITCHING SYSTEM.

Application fiIed June 7, 1915.

To all whom it may concern:

Be it known that I, HENRY PETER CLAU- SEN, a citizen of the United States, residing at Mount Vernon, in the county of Westchester and State of New York, have invented certain new and useful Improvements in Telephone Switching Systems, of which the following is a full, clear, concise, and eXact description. 4

This invention relates to telephone switching systems, and more particularly to a cord circuit for manual systems.

The object of this invention is to improve the service of manual exchanges by the provision of facilities for enabling the switchboard operator to make accurate observations of lapsed periods of time during which ringing current is applied to the line and during which the lines are actually connected for conversation.

In accordance with the first mentioned feature of this invention, there is provided for each cord circuit a timing device adapted .to operate automatically upon the application of ringing current to the called line, and to operate at different intervals an indicating device which will notify the operator that a certain time has lapsed since ringing current has been applied to the called line, thereby enabling her to keep the calling subscriber advised of conditions. Provision is also made for notifying the operator, by the use of the timing device,

- of a lapsed period of time during which the lines are actually in conversational connection. This is accomplished by the use of switching means operated when the called subscriber answers to restore and restart the timing mechanism and to associate therewith a signaling circuit which will be closed to indicate a period of lapsed time deter mined by the operator when setting up the connection with the cord circuit.

The timing mechanism may comprise a step-by-step rotating device adapted to be driven at difierent speeds by interrupters of diflerent characters and controlling circuit closing contacts during the time of one revolution. The speed at which the timing mechanism is driven during the ringing is preferably constant for all cords of one exchange, while the speed at which it is driven during the time that the lines are connected for conversation is predetermined by the Specification of Letters Patent.

Patented Feb. 6, 191?.

Serial No. 32,694.

operator in accordance with the class of service of the lines served.

The drawing is a diagram of a circuit and apparatus embodying the features of this invention.

In the drawing, 5 and 6 designate, respectively, calling and called subscribers telephone lines, each terminating in a jack 7 and having associated with it the usual telephone set and line signal and cutoff relays. A cord circuit, comprising conductors 8 and 9 terminating in plugs 10 and 11, has inserted in its conductors 8 and 9 condensers 12 and 13 for rendering the talking strands opaque to direct current. Supervisory relays 14: and 15, connected in bridge of the conductors 8 and 9 upon the side of the condensers 12 and 13 adjacent the calling line 5, are operated over the calling line, in a manner well known, to control a supervisory signal 16. Supervisory relays 17 and 18, connected with the talking strands 8 and 9 upon the side of the condensers 12 and 13 adjacent the called line 6, are oper ated in a similar manner to control a supervisory signal 19. A source of ringing current, indicated by signs, is adapted to be connected with called line 6 by means of a key 20, although this may be done automatically in a manner well known in the art. An o-perators telephone set 21 of well-known form may be connected in bridge of the cord strands 8 and 9 by means of a key 22.

Means are provided as follows for flashing the supervisory lamp 19 at difierent intervals during ringing, and also during the time that the lines are connected for conversation. A rotatable step-by-step circuitcontrolling device 25, actuated by means of a holding magnet 26 and a stepping magnet 27, is adapted to close successively contacts 28, 29 and 30 in its rotation to complete circuits from interrupters 31, 32 and 33 for operating the supervisory signal 19, and to close contact 53 when the lines are connected for conversation to operate the signal 19. Interrupting devices 84., 35 and 36 are provided for driving the step-by-step device 25 through one complete revolution at difl'erent predetermined rates of speed. When the plug 11 is inserted in the jack 7 of the called for line, the supervisory relay 17 will be energized over a circuit including the cord strand 9 and the winding of the supervisory relay, associated with the called line, to ground. Relay .17 operating closes its front contact 38 and completes a circuit from battery at 39, through supervisory lamp 19, contact 40 of a relay 41, winding of relay 42, back contact 43 of relay 18, front contact 38 of relay 17 and conductor 44, through winding of the holding magnet 26 to ground. Current in this circuit ener izes relay 42, closing contacts 45, 46 and 4 2 and opening contacts 48 and 49, and-also energizes holding magnet 26. The operation of magnet 26 draws a holding pawl 70 into engagement with the step-by-step element 25, and closes a contact 51. Upon the closure of the contact 51 there is completed a circuit for the stepping magnet 27, which may be traced from battery at 52 through the winding of the stepping magnet 27 contact 51, a normally closed contact 53, conductor 54, a back contact 55 of relay 41, a back contact 56 of relay 18 and interrupter 34 to ground. Assume that at the instant the plug 11 was inserted into the jack 7 of the called line, ringing current was connected with the called line 6, either by depressing the key 20 or automatically in any one of the well-known ways. This being the case, the operation of the interrupter 34 will cause current impulses to operate the stepping magnet 27 to move the step-by-step element 25 through one complete revolution in a period of time of, say, two minutes. As the step-by-step element 25 is rotated in response to these impulses, a contact arm 60 thereon is brought successively into engagement with the contacts 28, 29 and 30, the time of its engagement with these contacts being forty, eighty and one hundred and twenty seconds respectively. When the contact arm 60 reaches the contact 28, a circuit will be completed from battery 61 through interrupter 31, contact 45 of relay 42, contact 28, contact arm 60 and conductor 62 to a point 63. Current in this path shunts out the supervisory lamp 19 and causes it to flash in accordance with the interruptions of interrupter 31, thus notifying the operator that forty seconds have expired since the application of ringing current to the line. The operator may then notify the calling subscriber that she is calling the desired party. When the contact arm 60 reaches contact point 29, the operator will receive a signal in accordance with the interruptions of interrupter 32 notifying her that eighty seconds have expired since the application of ringing current to the line, and when the arm 60 reaches contact 30 the operator will receive a signal characteristic of interrupter 33 which will notify her that two minutes have expired since the applica tion of ringing current to the line, and it will be her signal to notify the calling subscriber that the-called party does not answer.

When the arm 60 of the step-by-step element 25 reaches the contact member 30, it strikes a stop member 65 and also a contact spring 66 and raises the latter to open the contact 53, thereby opening the circuit of the step,- ping magnet 27 in order to prevent chattering of the stepping magnet armature.

Upon receiving a request for a connection from the calling subscriber, the operator will, before completing connection to the called line, operate one of two keys 69 or 70 for completing a circuit from interrupt ers 35 and 36 which will he inefi'ective until the called subscriber has answered. The keys 69 and 70 are preferably the lock ing, or indicating type having three positions, a way-down non-locking position in which they control contact 71, an intermediate locki-ng position in which they close the circuit to the interrupters 35 and 36, and a normal or non-operated position. Assuming that the step-by-step element has traversed its full cycle without the called party responding and the calling party has requested a recall. The operator will make the recall merely by depressing key 69 or 70 into its way-down position to close the contact 71, thereby short-circuiting the holding magnet causing it to releasethe stepby-step element 25 which will be returned to normal by a spring or equivalent means. The deenergization of magnet 26 will also open contact 51 so that the stepping magnet will have no circuit until contact 51 is again closed. As soon as key 69 or 70 is released by theoperator, however, it will return to its midway or looking position, opening the contact 71 and completing the circuit for the holding magnet 26 previously traced, whereupon the operation of the step-by-step element 25 will be repeated. Should it happen though that the called for subscriber answers his signal by removing his receiver from the switch hook, relay 18 will become energized over a circuit including the wires of line 6. When this occurs, relay 18 will open contacts '43 and 56 and 82 and close contacts 7 3 and 74. The opening of contact 43 opens the circuit of relay 42 and the hold ing magnet 26, thereby releasing relay 42 and causing the restoration of the step-bystep element 25 to normal position. Belay 42' in releasing its armature opens the contacts 45, 46 and 47, and closes contacts 48 and 49. It will be noted, however, that relay 42 is made slow release by means of a copper sleeve 7 5 over its core, so that it will not close its contacts 48 and 49 until the stepby-step element has had time to restore to normal position. After both the contacts 48 and 7 3 are closed, however, by the energi Zation of relay 18 and the deenergization of relay 42, there will be completed a circuit for the relay 41 and the holding magnet 26 from the battery 7 6 through contact-48 of relay 42, contact 77 of relay 15 and contact 73 of relay 18 over conductor 44:. This will cause the energization of relay 41 and the holding magnet 26, thereby restarting the rotation of the step-by-step element 25 at a speed controlled by the interruptions of interrupter 35, assuming that key 69 has been depressed. The circuit for the stepping magnet 27 may be traced from battery at through contacts 51 and 53, conductor 54, contact 7 8 of relay &1, conductor '79 and con tact of key 69 to interrupter 35 and to ground. The interruptions from interrupter 35 will cause the stepping magnet 27 to drive the step-by-step element at a speed of, say, one revolution in three minutes. At the end of this period, contact arm 60 will have been brought into engagement with contact member 30, and a circuit will be completed for supervisory lamp 19 including the contact arm 60, contact member 30, contact 49 of relay l2 and an interrupter 80 to ground. The signal given by the lamp in response to the interrupter 80 will notify the operator that the allotted talking period of three minutes has expired, and the operator will notify the calling party to this ef feet. If the calling party desires to converselonger with the called party, he will notify the operator who will depress either key 69 or into its way-down position, restoring the timin device to normal in the manner hereinbei'ore described, and restart ing it to give a signal at the end of either three or live minutes, depending upon which of the keys, 69 or 70, was last depressed.

It will be noted that when the relay ll was operated, it completed a locking circuit for itself and the holding magnet through the contact 38 of relay 1'? associated with the called line. This is a precautionary measure provided for the purpose of preventing the calling party from restoring and restarting the timing mechanism by operating his switchhook to operate relay 15. The restoration of the subscribers receivers to their switchhooks will operate the supervisory signals 16 and 19 in the usual manner. Should it happen that the step-by-step element 25 is in a position of partial advancement at this time, the supervisory lamp 19 will be operated over a circuit in cluding a contact 82 of relay 1S and a contact 83 of relay 41.

What is claimed is:

1. In a telephone switching system, subscribers lines terminating in a central ofiice, a link circuit at the central oiiice for interconnecting said lines, a source of signaling current adapted to be connected with the called subscribers line, a timing mechanism adapted when started to operate for a predetermined time, means actuated upon the connection of the link circuit with the called line to start the timing mechanism, and a signaling device controlled by and operating at intervals during the operation of the timing mechanism to indicate to the operator that the called subscriber has not answered.

2. In a telephone switching system, subscribers lines terminating in a central ofice, a link circuit for interconnecting said lines, a source of signaling current adapted to be connected with the called subscribers line, a step-by-step timing mechanism adapted when started to operate for a predetermined time, an electromagnetic device actuated upon connection of the link circuit with the called line to start the timing mechanism, a signaling device, and a circuit for the signalingdevice completed upon the advancement of the step-by-step mechanism to predetermined positions to cause the signaling device to furnish signals at stated intervals.

3. In a telephone switching system, subscribers lines terminating in a central otfice, a link circuit at said central office for interconnecting said lines, supervisory signals associated with the answering and calling ends of said link circuit and controlled over the respective line circuits, a source of ringing current adapted to be connected with the called line, a timing mechanism associated with the calling end of the link circuit and driven at a predetermined rate of speed; and a plurality of branch circuits closed thereby at predetermined intervals and cOiltrOlliIlg the supervisory signal of this calling end of said link circuit to notify the operator that no response is made by the called subscriber after lapsed periods of time.

4. In a telephone switching system, subscribers lines terminating at a central oifice, link circuits thereat for interconnecting said lines, a source of ringing current at said central oi'tice adapted to be connected with acalled line upon the connection therewith of said link circuit, a timing mechanism operated automatically upon connection of ringing current with said line and embracing a rotatable contact member adapted to be driven through a complete revolution in a given interval of time, contacts closed successively by said rotatable member during its movement, a characteristic source of interrupted current individual to each of said contacts, and a signal adapted to be separately operated by the several interrupters for indicating diflerent periods of lapsed time from the application of ringing current to the line.

5. In a telephone exchange system, subscribers lines terminating at a central otfice, link circuits at said central oilice for interconnecting said lines, a'source of ringing current adapted to be connected with the called line upon the connection therewith of a link circuit, timing mechanism operated been connected for conversation for a predetermined allowable time.

(3. in a telephone switching system, subscribers lines terminating in a centraloflice,

a link circuit at said central oflice for interconnecting said'subscribers lines, a source oi ringing current adapted to be connected with the calling line, a signal, a plurality of normally open branch circuits including interrupters of different characters and said signal, a circuit closing element adapted to close said branch circuits successively, means for driving said circuit closing element at a predetermined rate of speed during the connection of ringing current with the line, means controlled from the called subscribers station for resetting said circuit closing element upon the response of the calledsubscriber, means for driving said circuit closing element at a different rate of speed when the lines are connected for conversation, said means being rendered efiective upon the response of the called subscriber,

Copies of and a circuit for said signal closed bysaid circuit closing element after the lapse of a period of time determined by said second connected driving means.

7 In a telephone switching system, calling and called subscribers lines terminating at a central office, a link circuit at the central oilice for interconnecting said lines, supervisory signals associated with the answering and calling ends of said link circuit, relays for each of said signals controlled over the subscribers lines, a source of ringing current adapted to be connected with the called subscribers line, a circuit closing element, a circuit for the supervisory signal associated with the calling end of the cord circuit adapted to be closed by said circuit closing element, interrupters for driving said circuit closing element at different speeds, circuit connections controlled in one position of a supervisory relay associated with the calling end of said link circuit for causing said circuit closing element to be driven from one of said interrupters, circuit connections controlled in another position of said supervisory relay to restore said circuit closing element to normal and restart it from a different speed interrupter, and circuits for said supervisory signal closed by said circuit controlling device.

In witness whereof, I hereunto subscribe my name this 3rd day of June A. D., 1915.

HENRY PETER GLAUSEN.

this patent may be obtained for five cents each, by addressing the "Commissioner of Patents,

Washington, D. .G. 

